Switching in a telecommunications network or in general within a communications network allows one subscriber to connect with any other subscriber in the network and organises the flow of information between the subscribers so that they can communicate with each other.
One particular type of switching is called circuit switching where subscriber information is normally assigned to time slots and the actual switching is performed on these time slots. Thus, a switch, commonly known also as a Group switch, handles time slots such that subscriber information is switched or connected from an input point of the switch to an output point of the switch. The basic building blocks of such circuit switches are generally time (T) switch stages and space (S) switch stages. By combining the time switch stages and space switch stages in different ways, a variety of switch structures are obtained. Examples of such switch structures are time-space-time (TST) switches, space-time-space (STS) switches, time-space (TS) switches, TSST switches and SSTSS switches.
TS switches are of particular interest as they have a number of advantages including that these type of switches are inherently non-blocking for point-to-point connections as well as for broadcasting. This is not the case for other type switches. Furthermore, the TS switch structure has short delay through the switch and simple path selection.
Furthermore, speech store memories that are commonly utilised in TS switches have become faster and less expensive, thus making the TS switch structure interesting also for larger switches.
However, due to the large amount of internal connections between the speech store memories, control stores and multiplexers in a TS switch, the internal components of a TS switch have to be arranged tightly together in order to practically realise all connections. For this reason, the TS switch usually has to be provided in a single sub rack. Therefore, the size of the sub rack, memory performance and amount of required interconnections limits the maximum capacity of a TS switch. Conventional large TS switches have a capacity of 128 K, although high capacity is possible when the technology is stretched to its limits squeezing as many components and cable connections as possible into the same sub rack. In many telecommunication applications, higher capacities such as 256 K or 512 K are required, making the conventional TS switch structure insufficient.
Furthermore, the existing TS switches do not provide an efficient and simple technique for increasing capacity to large capacity TS switches ranging in size beyond 128 K.
It is an object of the present invention to address at least one problem associated with the prior art.
It is a further object of the present invention to provide an improved switch.